Motor vehicles generally feature side door windows which can be moved between lower (opened) and upper (closed) positions. The mechanism used to move the window between these upper and the lower positions is generally known as a window regulator. A window regulator is arranged inside a vehicle door below the window opening. The window regulator can either be manually operated by a person or driven by a powered actuator, most commonly an electric motor.
One type of window regulator utilizes a pulley system. This pulley system uses a metal cable guided around a drum coupled to an electric motor or hand crank to drive a carrier that is fastened to the window and engages a guide rail to control motion as the carrier moves vertically. The drum is rotatably mounted to a drive unit housing. In order to remove slack in the metal cable outside the drive unit housing, the cable extends through a cable sheath. The sheath terminates in a connector with a compression spring, also called spring cap. The connector is inserted into a corresponding port in the drive unit housing so that the compression spring is operatively arranged between the connector and the port. The compression spring takes up slack of the cable forming the core of the cable sheath and, due to its compressibility, reduces cable tension during operation of the window regulator when the cable is moving.
The use of sheathed cables has eliminated the need for a straight, tensioned cable path because sheathed cables, also called Bowden cables or push-pull cables, have the advantage of retaining the cable tension around bends. It has been found, however, that such a bent sheathed cable may vibrate when the door is slammed shut due to the added degree of freedom of the cable to swivel about the axis intersecting the connectors at the ends of the sheathed cable. The movement of the cable results in a rattle noise that is generally perceived as unpleasant and may convey a false impression of loose parts.
Therefore, it is desirable to mitigate the rattling noise caused by the bent sheathed cable.